Continuous casting machine for slabs

ABSTRACT

A continuous casting machine for slabs includes a mold that has a mold passage of trapezoidal cross section with the base surface on the side of the center of curvature of the casting and the opposite surface being symmetrically arranged about the central plane of the mold passage.

I Umted States Patent 1 1 3,580,325

[72] Inventor Hans Schrewe [51] Int.Cl... 0. 822d 11/00 Duisburg-Ungelsheim, Germany [50] Field of Search 164/82, 87,

[21] Appl No, 813,171 2 3.278,28l.282,283; 18/10 [22] Filed Apr. 3, 1969 n [45] Patented May25, 1971 1 References Cited [73] Assignee Mannesmann Aktiengesellschaft UNITED STATES PATENTS Dusseldmflcermany 2,206,930 7/1940 Webster l64/278X [321 Pmmy May 1965 3,358,744 12/1967 Rossi 164/282 [33] Germany 3 1 52 Primary ExaminerJ. Spencer Overholser Continuation-impart of application Ser. No. 550,713, May 17, 1966, now abandoned.

[54] CONTINUOUS CASTING MACHINE FOR SLABS 7 Claims, 7 Drawing Figs.

Assistant Examiner-R. Spencer Annear Attorney-Ernest F. Marmorek ABSTRACT: A continuous casting machine for slabs includes a mold that has a mold passage of trapezoidal cross section with the base surface on the side of the center of curvature of the casting and the opposite surface being symmetrically arranged about the central plane of the mold passage.

PATENTEU W25 IBYI 3580.325

sum 2 ur 2 Fig.5

"FIL

Fig. 6 Fig. 7

, V i Addition for 7 Defamation (inclination i) CONTINUOUS CASTING MACHINE FOR SLABS This application is a continuation-in-part of my copending application Ser. No. 550,713, filed May l7, I966, now abandoned.

The invention relates to the continuous casting of metal, and relates more particularly to the continuous casting of metal in a mold that is externally cooled, for instance a liquid cooled mold, the axis of mold space of which is either straight or arcuate. Still more particularly, the instant invention relates to the continuous casting of metal of rectangular cross section, such as slabs or wide billets, in such a mold.

During the casting of ingots, as well as during the continuous casting of metals such as iron and steel, the cross section of the casting generally corresponds to the cross section of the mold in which the metal is cast. For this reason, in the art of the continuous casting of iron and steel either in vertical casting plants, or in plants with an arcuate path for bending the casting towards the horizontal, including the casting of slabs, the mold in the past was given the same type cross section as the cross section of the finally formed casting. During the continuous c8sting of rectangular slabs in casting plants of the aforesaid type, wherein the slabs were lowered in a curved path, in which the curvature and, respectively, the straightening occurred in a region of the slab in which the core thereof was still at least in part liquid, and thus the slab was not completely solidified, it has been found that, with the methods and apparatus heretofore used, there could no longer be obtained a finished casting with an accurate rectangular cross section.

This deviation from the expected final cross section has led to various difficulties during the further working of the slabs, for instance during the rolling process and the heat treatment necessary therefor.

In the molds of the prior art the mold passage was of rectangular cross section, intending to yield a final crosssection of rectangular shape after the slab has been brought into the horizontal direction. Thus, a mold of rectangular cross section was employed in the endeavor to yield a final rectangular shape. It has been found, however, that a mold of rectangular cross section does not yield a final rectangular slab shape. Actually, it was discovered that the final shape had trapezoidal form. It is assumed that this change in shape resulted from a difference in guiding the curved and subsequently straightened slab between the two wide sides of the same slab. As a result, the end surfaces of the slab were inclined relative to each other, rather than parallel.

The instant invention aims to avoid this drawback, and to have a rectangularly shaped slab as its end product. To accomplish this, it has been found that the mold passage can no longer have a rectangular cross section; instead, the instant invention provides for a mold passage of trapezoidal shape that will yield a slab of rectangular cross section after it has been guided through and out of the curvature.

It is accordingly among the principal objects of the invention to provide a continuous casting machine and mold that will avoid the drawbacks of the prior art referred to.

It is another object of the invention to provide a continuous casting machine and mold which is so constructed that it will produce a casting that will have in the end the expected crosssectional dimensions.

It is a further object of the invention to provide a continuous casting mold that has a main wide wall disposed on the side of the center of curvature of the billet, which curvature the billet will assume at least after it has left the casting mold, making that main wide wall larger than the wide wall opposite thereto.

It is still another object of the invention to provide such a mold, the narrow walls of which will no longer be parallel to each other but fonn an angle with each other.

Further objects and advantages of the invention will be set forth in part in the following specification and in part will be obvious therefrom without being specifically referred to, the same being realized and attained as pointed out in the claims hereof.

With the above and other objects of the invention in view, the invention consists in the novel construction, arrangement and combination of various devices, elements and parts, as set forth in the claims hereof, certain embodiments of the same being illustrated in the accompanying drawings and described in the specification.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary schematic side elevational view, showing a curved mold for continuous casting and the continuous casting emerging therefrom;

FIG. 2 is a fragmentary side elevational view, similar to FIG. 1, but showing a mold with an inclined straight axis;

FIG. 3 is a fragmentary plan view, partly in section, showing the mold and trapezoidal slab in section, taken on the line 3-3 of FIG. 1;

FIG. 4 is a sectional view of the still trapezoidal casting,

taken on the line 4-4 of FIG. I, in which the casting is still being curved;

FIG. 5 is a sectional view of the slab having assumed rectangular shape, taken on the line 5-5 of FIG. 1, after the slab has been straightened;

FIG. 6 is a sectional view of FIG. 1; and

FIG. 7 is a sectional view of the mold, similar to FIG. 6, but taken on the line 7-7 of FIG. I.

In carrying the invention into effect in the embodiments which have been selected for illustration in the accompanying drawings and for description in this specification, and referring now particularly to FIGS. 1 and 2, there is shown a mold 1 in FIG. 1 with a curved mold space axis; and a similar mold I in FIG. 2 which, however, has a mold space axis that is inclined to the vertical. The slab 2 that is cast in the molds l, 1', respectively, descends at least after it leaves the mold in a curved path until it reaches a substantially horizontal direction; during that time and path, the core of the slab is still at least in part liquid, as shown at 3 in FIGS. 1,2 and 3.

The center of curvature of the slab 2 is shown at X, with a radius of curvature R in FIG. 1, and at Y with a radius of curvature R in FIG. 2.

The mold has a plurality of sidewalls, for instance four sidewalls, namely two opposite wide sidewalls 4 and 5, and two opposite narrow sidewalls 6 and 7. The main wide wall 4 (FIG. 1; 4', FIG. 2) is disposed on the side of the center ofcurvature of the slab 2, while the other wide wall 5 (FIG. I; 5', FIG. 2) is disposed opposite thereto relative to the casting in the mold.

Guide means, such as guide rolls 11 are shown schematically in FIGS. 1 and 2, for guiding the slab 2 past the curvature at least into the initiation of the straightening. The rolls 11 are of conventional construction, and perform the same function that they perform in devices of the prior art; except that they now receive from the mold 1, I a casting that is shaped trape zoidally rather than rectangularly, and which, upon completing its run through the guide means, will assume in the end a rectangular shape.

As best shown in FIG. 3, the invention provides that the form-giving part, namely the internal surface of the wide main wall 4 (FIG. I; 4, FIG. 2) which, relative to the casting inside the mold, is disposed on the side of the center of curvature of the slab 2, is larger than the opposite form-giving part, namely the internal surface of the opposite wide wall 5 (FIG. 1; 5', FIG. 2) of the mold l, 1', respectively. The form-giving internal surfaces of the narrow walls 6 and 7 of the mold l, l', in accordance with the invention are not parallel to each other, but form an angle with each other; thus, the cross section of the interior of the mold l, 1' forms a regular trapezoid, the basis of which is disposed on the side of the center of curvature of the slab 2.

As may clearly be observed in FIG. 3, the mold passage is of trapezoidal cross section, with the base of the trapezoid facing ofthe mold, taken on the line 6-6 the center of curvature X. Y (FlGS. l, 2). The trapezoidal nature of the mold passage is also clearly observable from FIGS. 4 and 5. In FIG. 4 it can be seen that on the passage from upright to horizontal position, the slab will pass through a phase at which it is of a less pronounced trapezoidal shape; until it reaches rectangular shape, as shown in FIG. 5.

The opposite side of the trapezoid base is substantially symmetrically arranged about the central plane W-W of the mold passage; said central plane W-W extends from the mold to the center of curvature X, Y.

[n referring here n to the center of curvature, this has been illustrated as a single axis X, Y. Actually, this may be but an approximation, as the curvature may have several adjoining sections of different radii, for example as shown in the patent to Bungeroth and applicant, U.S. Pat. No. 3,324,931, dated June 13, 1967. The term center of curvature herein therefore includes the designation of a central region, as well as a specific axis. Where, however, a definite radius is indicated herein, the center of curvature is substantially an axis.

The trapezoidal inclination of the form-giving parts, namely the internal surfaces of the narrow sidewalls 6 and 7 of the mold l, l, which may also be referred to as addition for deformation (i), takes into account in advance the subsequent changes of the casting that are brought about by deformation, while the inward offsetting of the form-giving parts, namely of the internal surfaces of the narrow sidewalls 6, 7 (FIGS. 6, 7), takes into account the tapering that is generally present at molds for continuous casting.

The inclination (i), designated in the foregoing as addition for deformation, of the form-giving parts, namely of the internal surfaces of the sidewall 6, 7, depends on the width of the slab, the speed of casting and, at curved molds, on the casting radius.

Example It has been found that when molds are used with a curved axis of mold space, and which is designed for a slab having a width of about 1,500 mm., that there exists a dependency of the aforesaid addition for deformation from the radius of casting in such a manner that at a radius of 8 m., there was an addition for deformation of about 1 percent of the median slab width;

at a radius of 6 m., about 1.5 percent;

at a radius of4 m., about 2 percent; and

at a radius of 2 m., about 2.5 percent are necessary.

The casting speed was 650 mm., per minute during the casting of a normal carbon steel.

lwish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire to be secured by Letters Patent, is as follows:

1. A continuous casting machine, for use in the continuous casting of slabs of rectangular cross section, comprising in combination,

a liquid cooled upright mold open at the top and bottom,

and

guide means guiding each slab and curving it at least after it leaves the mold, at least partially in accordance with a predetermined curvature about a center of curvature into a substantially horizontal direction while the core of the slab is still at least in part liquid,

said mold comprising a plurality of walls defining a mold passage of regular trapezoidal cross section with the base of the trapezoid disposed facing said center of curvature, the opposite side of said trapezoid being disposed opposite said space and arranged relative thereto substantially symmetrically about the central plane of said mold passage, said central plane extending from the mold passage to said center of curvature, the end surfaces of said trapezoidal mold being so inclined that said slab deforms to a rectangular shape during passage from the u right to the horizontal direction, sal guide means guiding said slab past the curving of the straightening slab through the initiation of the straightening at least at which latter point said slab will have assumed a shape of rectangular cross section,

the width of the slab after it has assumed rectangular cross section being smaller than the length of said base but larger than the length of said opposite side at the beginning of the mold passage.

2. A continuous casting machine, as claimed in claim 1, the area of cross section throughout the direction of said mold passage of said slab decreasing in accordance with predetermined tapering of the surface of said wall.

3. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 8 meters and i about 1 percent.

4. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 6 meters and i about 1.5 percent.

5. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 4 meters and i about 2 percent.

6. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 2 meters and i about 2.5 percent.

7; In a method of continuously casting slabs having a rectangular endcross section, the steps comprising forming the casting uprightly with initial trapezoidal cross section shape,

thereafter guiding the casting throughout a curvature into a substantially horizontally direction while the core of the casting is still at least in part liquid,

the base of the trapezoid being disposed facing the center of said curvature, and the opposite side of said trapezoid being relative thereto arranged substantially symmetrically,

whereby near the passage into the horizontal said casting will have a rectangular cross-sectional shape. 

1. A continuous casting machine, for use in the continuous casting of slabs of rectangular cross section, comprising in combination, a liquid cooled upright mold open at the top and bottom, and guide means guiding each slab and curving it at least after it leaves the mold, at least partially in accordance with a predetermined curvature about a center of curvature into a substantially horizontal direction while the core of the slab is still at least in part liquid, said mold comprising a plurality of walls defining a mold passage of regular trapezoidal cross section with the base of the trapezoid disposed facing said center of curvature, the opposite side of said trapezoid being disposed opposite said space and arranged relative thereto substantially symmetrically about the central plane of said mold passage, said central plane extending from the mold passage to said center of curvature, the end surfaces of said trapezoidal mold being so inclined that said slab deforms to a rectangular shape during passage from the upright to the horizontal direction, said guide means guiding said slab past the curving of the straightening slab through the initiation of the straightening at least at which latter point said slab will have assumed a shape of rectangular cross section, the width of the slab after it has assumed rectangular cross section being smaller than the length of said base but larger than the length of said opposite side at the beginning of the mold passage.
 2. A continuous casting machine, as claimed in claim 1, the area of cross section throughout the direction of said mold passage of said slab decreasing in accordance with predetermined tapering of the surface of said wall.
 3. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 8 meters and i about 1 percent.
 4. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 6 meters and i about 1.5 percent.
 5. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 4 meters and i about 2 percent.
 6. A continuous casting machine, as claimed in claim 1, for wide slabs, said curvature being along a radius R about said center of curvature, the end surfaces of said trapezoidal mold passage being inclined in accordance with an addition of deformation i expressed in percentage of median slab width, R being about 2 meters and i about 2.5 percent.
 7. In a method of continuously casting slabs having a rectangular end cross section, the steps comprising forming the casting uprightly with initial trapezoidal cross section shape, thereafter guiding the casting throughout a curvature into a substantially horizontally direction while the core of the casting is still at least in part liquid, the base of the trapezoid being disposed facing the center of said curvature, and the opposite side of said trapezoid being relative thereto arranged substantially symmetrically, whereby near the passage into the horizontal said casting will have a rectangular cross-sectional shape. 